  var  MMBackgroundLayer = cc.Layer.extend({

  	   _sptBg      :  null,
  	   _sptLogo    :  null,
  	   _ship       :  null,
  	   ctor : function(){

  	   		this._super()

  	   		cc.spriteFrameCache.addSpriteFrames(res.TextureTransparentPack_plist);

  	   		this.initBackgronud();

  	   		this.initShip();

  	   		this.initLogo();
  	   },

  	   initBackgronud : function(){

  	   	this._sptBg = new cc.Sprite(res.mm_bg_png);
  	   	this._sptBg.attr({
  	   		anchorX : 0.5,
  	   		anchorY : 0.5,
  	   		x: GC.w_2, 
  	   		y: GC.h_2
  	   	});
  	   	this.addChild(this._sptBg);
  	   },

  	   initLogo : function(){
  	   	this._sptLogo = new cc.Sprite(res.mm_logo_png);
  	   	this._sptLogo.attr({
  	   		x: GC.w_2,
  	   		y: GC.h - 160
  	   	});
  	   	this.addChild(this._sptLogo);
  	   },
  	   initShip : function(){
  	   	  this._ship = new cc.Sprite("#ship01.png");
  	   	  this.addChild(this._ship);
  	   	  this._ship.x = Math.random() *GC.w;
  	   	  this._ship.y = 0; 

  	   	  this._ship.runAction(cc.moveBy(2, cc.p(Math.random()* GC.w, this._ship.y + GC.h + 100)));
  	     
  	      this.schedule(this.update, 0.1);	 
  	   },
  	   update : function(){
  	   	if(this._ship.y > 480){
  	   	   this._ship.x = Math.random() * GC.w;
  	   	   this._ship.y = 10;
  	   	   this._ship.runAction(cc.moveBy(
  	   	   		parseInt(5  * Math.random(), 10), 
  	   	   		cc.p(Math.random() * GC.w, this._ship.y + 480)	
  	   	   	));	
  	   	}
  	   }
  });